In a seminal paper, Kohn and Luttinger (KL) [1]} explored how superconductivity arises from repulsive interactions. They considered a 3d electron gas with weak short-ranged repulsive interactions, for which they identified
an instability to an unconventional superconducting state with non-zero Cooper pair angular momentum.
In particular, they emphasized the role played by Friedel oscillations associated with the existence of a sharp Fermi surface.
Below, we provide a modern discussion of the problem in the language of the renormalization group (RG), and show that (in contradistinction to the KL analysis) the structure of the particle-hole susceptibility at all energy scales, not just close to the Fermi level, dertermines the superconducting instabilities [2]}, [3]}. For a recent reviews on superconductivity from repuslive interactions, consult Refs.  [4]}, [5]} and references therein.
